On Wednesday, October 7, 2026 at 6:18:53 PM UTC+3 Rick Byers wrote:
Looks good to me, but is there any reason this PR can't land now? It needed some more work. It has landed now. On Wed, Sep 30, 2026 at 5:35 PM Alex Russell <[email protected]> wrote: LGTM1; this is an awesome addition. Thanks for making it happen. On TAG review, can you please send an FYI? Best, Alex On Wednesday, September 30, 2026 at 2:47:22 PM UTC+1 Yoav Weiss wrote: *Contact emails* [email protected] *Explainer* https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369 *Specification* https://github.com/w3c/long-animation-frames/pull/30 *Summary* Add `styleDuration` and `forcedStyleDuration` information to the Long Animation Frame API, enabling developers to distinguish style and layout times. *Blink component* Blink>PerformanceAPIs <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%22> *Web Feature ID* Missing feature - https://github.com/web-platform-dx/web-features/ issues/4453 *Motivation* Currently performance-conscious developers have no way to distinguish their style time from their layout time, making CSS performance issues less actionable than they can be. This feature enables developers to make that distinction. *Initial public proposal* https://github.com/w3c/long-animation-frames/pull/30 *TAG review* I didn't file for a TAG review as these are a few new attributes that break up the timings provided by an existing attribute, mimicking its existing shape. I don't expect the TAG to have strong opinions on the shape of the attributes. *TAG review status* Not applicable *Origin Trial Name* Long Animation Frames - separate style and layout durations *Goals for experimentation* See that the new attributes provide useful data to developers as they debug their CSS performance issues. *Chromium Trial Name* LongAnimationFrameStyleDuration *Link to origin trial feedback summary* https://groups.google.com/a/chromium.org/g/blink-dev/c/ qvGqBcSOFTQ/m/rU6rqKuMCAAJ *Origin Trial documentation link* https://github.com/w3c/long-animation-frames/pull/30#issue-3828859369 *WebFeature UseCounter name* kLongAnimationFrameTimingStyleDuration *Risks* *Interoperability and Compatibility* *As these are new attributes, I don't expect them to have any compat impact. As far as interop goes, I'd expect that when other engines adopt LoAF, they'd also adopt these attributes.* *Gecko*: No signal Positive on the broader LoAF: https://github.com/mozilla/ standards-positions/issues/929 I'm asking if I should file a more specific issue for these extra attributes. *WebKit*: No signal (https://github.com/WebKit/standards-positions/ issues/283) No signal for the broader LoAF feature. Unlikely they'd have a strong position on these attributes. *Web developers*: Positive (https://groups.google.com/a/chromium.org/g/ blink-dev/c/qvGqBcSOFTQ/m/5DCTOu9KCgAJ) *Other signals*: *WebView application risks* Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? *No information provided* *Debuggability* *No information provided* *Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?* Yes *Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* Yes - https://wpt.fyi/results/long-animation-frame/loaf-style-duration.html: styleDuration (9 subtests) - https://wpt.fyi/results/long-animation-frame/loaf-layout-duration.html: layoutDuration (7 subtests) - https://wpt.fyi/results/long-animation-frame/loaf-forced- style-duration.html: forcedStyleDuration (4 subtests) - https://wpt.fyi/results/long-animation-frame/loaf-forced- layout-duration.html: forcedLayoutDuration, including checking that forced style plus forced layout adds up to forcedStyleAndLayoutDuration (5 subtests) - https://wpt.fyi/results/long-animation-frame/loaf-container-queries.html: all four attributes when container queries mix style and layout work (6 subtests) - https://wpt.fyi/results/long-animation-frame/loaf-toJSON.html: now also checks styleDuration and layoutDuration in toJSON() *Flag name on about://flags* *No information provided* *Finch feature name* LongAnimationFrameStyleDuration *Rollout plan* Will ship enabled for all users *Requires code in //chrome?* False *Tracking bug* https://issues.chromium.org/issues/476826067 *Estimated milestones* Shipping on desktop157Origin trial desktop first148Origin trial desktop last 153Shipping on Android157Shipping on WebView157 *Anticipated spec changes* Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way). *No changes expected.* *Link to entry on the Chrome Platform Status* https://chromestatus.com/feature/5171478175809536?gate=6516503656660992 *Links to previous Intent discussions* Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink- dev/CAOmohSJxRuMp6Ha5RVCjzNfsG0Sj96Y%3Dgy9LnxtM%2Brq-S6DEew%40mail.gmail.com Intent to Experiment: https://groups.google.com/a/ chromium.org/d/msgid/blink-dev/CAOmohSJ2PJ0dZxYH48PALOSUenSSV 7VuZ9CzTHnGd8u_jTKkcg%40mail.gmail.com This intent message was generated by Chrome Platform Status <https://chromestatus.com/>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/ chromium.org/d/msgid/blink-dev/9403784c-3fb5-47a6-b288- d6c4c26945bdn%40chromium.org <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/9403784c-3fb5-47a6-b288-d6c4c26945bdn%40chromium.org?utm_medium=email&utm_source=footer> . -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/8cd3ccdd-657d-448a-83f9-363b14e03d94n%40chromium.org.
